Directional receiver



April 1942- P. G. COOPER ET AL 2,279,021

DIRECTIONAL RECEIVER Filed Nov. 50, 1959 2 Sheets-Sheet 1 RECEIVE)? .D- (LL 0/73 HIGH VOLTHGE' 7'0 ac. LO/ZD 3nventots Philip GzCooper Clarence April 7, 1942- P. G. COOPER ETAL 2,279,021

DIRECTIONAL RECEIVER Filed Nov. 30, 1939 2 Sheets-Sheet 2 HECE/ VL'I? zzaLww 5 HECE/VE'I? Q W Philip G. 60022 By Clarence D. Tw-slia 61 Patented Apr. 7, 1942 x UNITED STATES PATENT OFFICE DIRECTIONAL RECEIVER of Delaware Application November 30, 1939, Serial No. 306,828

Claims.

This invention relates to directionalradio receivers, and particularly to an improved directional receiver of the type which utilizes a directional and a nondirectional antenna to produce alternately a pair of distinctive directional response patterns of the intersecting type.

In accordance with the well known practice, a directional receiver is provided in which currents from a directional antenna, usually a rotatable loop, are combined in the proper phase relation with currents from a nondirectional antenna. By periodically reversing the phase of the currents from one of the antennas and at the same time reversing the direction of currents which energize an indicating output meter the sense of the deviation of the loop from a predetermined orientation is made known.

The periodic switching of the loop antenna current may be accomplished mechanically or electronically. A mechanical system, for example, is described in United States Patent No. 2,054,160, for a Directional receiver issued to A. Leib on September 15, 1936, while an example of the electronic switching system is to be found in a German Patent No. 482,281, issued to Dieckmann et al. on September 11, 1929.

In accordance with the present invention the electronic or mechanical means which performs the switching function is also used as a rectifier to supply direct current for operating the receiver, thus eliminating the conventional rectifier tube. The system is suitable for use with alternating current operated receivers or battery operated receivers which employ vibrator interrupters.

The primary object of this invention is, therefore, to provide an improved direction finder. Other objects of this invention include the provision of means for combining the function of rectifying and switching in a left-right indicator; the provision of novel means for supplying direct current for the operation of a directional receiver; and the provision of means for causing the alternating current power source to synchronously operate the input and output switching systems of a left-right indicator and at the same time to develop a direct current suitable for operating the .apparatus. Further objects of this invention, as well as a more complete understanding of its nature and operation will he obtained from the following description when considered in connection with the accompanying drawings. Its scope is indicated by the appended claims.

Referring to the drawings, Figure l is an embodiment of this invention utilizing a mechanical switching arrangement; Figure 2 is a schematic drawing of a mechanical switch suitable for this purpose; Figure 3 is a modified form of receiver using a pair of diode rectifiers; and Figure 4 is a preferred embodiment utilizing a pair of triode tubes for switching the loop antenna and for providing the direct current for the receiver operation. Similar reference numerals are applied to similar elements.

Referring to Fig. 1, an arrangement is illustrated in which a vibrating interrupter and rectifier unit is used to produce high voltage direct current from a low voltage direct current source, and at the same time to alternately reverse the antenna and receiver output connections by means of auxiliary contacts mounted on the vibrator. Specifically, a loop antenna 5 has a point 1 intermediate its ends grounded and its terminals connected to two fixed contacts 9 and H of a switch l6. A contact element 15 is insulatingly mounted on the movable switch arm. i

In one position the contact element [5 connects fixed contact 9 to a third fixed contact l3, and in the other position connects fixed contact I! to a fourth fixed contact I4. The third and fourth fixed contacts are connected through an input coil I! to ground. Input coil I1 is coupled to the input of a receiver IS. A nondirectional antenna 2| is also coupled to the receiver input so that signal currents from the two antennas are combined, their relative phase depending upon the position of the switch contact It. That is, the currents in the two halves of the loop 5 are in phase opposition, and the resultant signal amplitude which is applied to the receiver is, therefore, a function of the position of the switch contact I5.

The indicating meter 23 is a zero center milliammeter. .It is connected to the receiver output through a device for periodically reversing the polarity of the applied currents. A suitable arrangement includes a switch 25 for connecting the meter across either half of the secondary of an output transformer 21.

Direction finders of this type are primarily intended for use on boats and airplanes. Such crafts are frequently equipped with storage batteries as their prime power source. Consequently, the prime power source in the present example is assumed to be a storage battery 29. In orderto provide high voltage direct current for operating the receiver IS, the primary current from the battery is interrupted periodically by a vibrator type interrupter 3|, stepped up to the desired voltage by a transformer 33, and rectified by a mechanical rectifier 35. An example of such a vibrator-rectifier arrangement is described and claimed in Patent No. 2,063,311, for Electrical vibrator unit, issued to E. C. Guedon et a1., December 8, 1936, on an application filed February 28, 1934. p

In accordance with the present invention, the antenna and output phase reversing switches l6 and 25 are operatively connected to the Vibrating interrupter 3i which acts as a prime mover for the switches. Preferably, the phase reversing switches I6 and 25 are made apart of the vibrator mechanism. This may be accomplished readily since a considerationof the circuit indicates that with the exception of the movable contact l of the antenna reversing switch, all the movable contacts are at ground potential. An arrangement for mounting the various contact points is illustrated in Fig. 2, to which reference is now made.

A single grounded metallic armature 31 is resiliently mounted for limited vibration about an axis 39. The armature carries a suitable number of movable contact points for engagement with juxtaposed contact points, which may be yieldably mounted, to form the operating elements of the vibrator-interrupter switch 3|, the high voltage rectifier 35, and the receiver output phase reversing switch 25. In addition, the movable contact 15 of the antenna reversing switch It is insulatingly mounted on the armature 31 by means of a suitable insulating material 4!. The displacement of the various contact elements along the length of the armature has been illustrated merely for convenience. In practice, the contacts would be located near the free end of the armature in the manner illustrated in Fig. 1 of the above identified Guedon patent.

As a result of the arrangement shown, the antenna and receiver output switches are automatically synchronized, and the power required to operate them is derived from an already existing source, thus simplifying and reducing the size and weight of the equipment.

When a source of alternating current power is available, or where an electronic switching arrangement is desired, the embodiment illustrated in Fig. 3 is proposed. In this case, a pair of diode rectifiers, or a single tube having the equivalent electrodes, is used to rectify the high voltage alternating current for the operation of the receiver, and at the same time to key synchronously the antenna input. The receiver output is effectively keyed by an alternating voltage of the frequency of the power source.

Except for the dual function of the keying tubes and the use of two electrode tubes, the proposed'circuit is similar to that illustrated in an article by Hell published in the 1929 German J ahrbuch, vol. 33, No. 4. A directional antenna 5 is grounded at its midpoint l and has its two terminals coupled, respectively, to the anode electrodes of a pair of diode rectifiers 43 and 45. The two cathode electrodes of the tubes are coupled through a blocking capacitor 47 to an input coil H which is coupled to the receiver is input circuit. A nondirectional antenna 2| is also coupled to the receiver input. The rectifier cathodes are connected to ground through a radio frequency choke 39 and by-pass capacitor 5i. The terminal of the radio frequency choke remote from the cathodes is connected through a filter including a reactor 53 and an electrolytic capacitor 55 to the high voltage connection of the receiver l9.

The D. C. path from the rectifier cathodes to ground is completed through the D. C. load of the receiver, which may include a bleeder resistor.

The two anode electrodes of the rectifier tubes 43 and 45 are also connected, respectively, to the secondary terminals of a high voltage power transformer 33. A pair of radio frequency choke coils 51 and 59 are included in each anode circuit to isolate the radio frequency voltages which are impressed on the anodes by the loop antenna from the secondary winding of the power transformer 33. The center tap of this transformer secondary is grounded.

The primary of the power transformer is energized by any suitable source of alternating current, such as a generator 6|, although it is to be understood that a battery and interrupter system of the type illustrated in Fig. 1 could be used. A voltage derived from the alternating current source is applied'to the phasing coil 63 of a left-right indicator meter 65. The deflecting coil El is connected to the receiver output.

A consideration of the circuit diagram of Fig. 3 will make it clear that the rectifier tubes 51, 59 will cause a high positive potential, with respect to ground, to appear on the cathode electrodes, which voltage will charge the by-pass capacitor 5i and the electrolytic capacitor 55. The amplitude of this voltage will tend to approach the peak amplitude of the applied alternating potential, but will actually reach some value below the peak amplitude, depending on the time constant of the associated circuit. During alternate portions of each successive cycle each rectifier becomes momentarily conductive, and during the moment of conductivity, a radio frequency current will flow from the corresponding half of the loop antenna through the input coil I! to ground. This received impulse is used to energize the defiecting coil of the output meter, and at the same time the meter polarity is synchronously reversed to provide left-right indication in the well known manner.

In a preferred embodiment of our invention, improved performance, as a result of greater radio frequency gain, is achieved by utilizing triode rectifiers. One reason for the improved performance is that the signal-noise ratio is improved when the radio frequency gain ahead of the receiver input is increased Another reason is that the high input impedance of the triodes allows the full gain of the loop antenna to be utilized.

Referring to Fig. 4, the loop antenna 5 is connected to the grid electrodes of a pair of keying triodes 69 and H. The anode electrodes of the tubes are connected in parallel 'at radio frequency by a pair of small capacitors I3 and 15, while being isolated from the remainder of the circuit by a pair of radio frequency chokes H and 19. The alternating voltages of power frequency from the power transformer 33 are applied through chokes 11 and 79 in phase opposition to the same anode electrodes.

The cathode electrodes of the keying tubes, as before, are the source of the high direct current potential for operating the receiver. A bleeder resistor BI is connected across the direct current source from which a biasing voltage for the grids of the keying tubes is derived. Since the cathodes are at quite a high positive potential, the grids are returned to a point of lower positive potential on the bleeder resistor 8i. In other respects the connections of this arrangement are the same as those described in connection with Fig. 3.

In operation, the cathodes assume a positive potential, with respect to ground, which is somewhat less than the peak of applied peak plate voltage by reason of the constant fiow of current through the receiver I9 and bleeder 8|. Consequently, during alternate portions of each cycle, the keying tubes are impressed with a positive anode potential which exceeds the cathode potential so that grid control is established and the tube functions normally as a grid controlled amplifier. Amplified signals from opposite halves of the loop are, therefore, alternately impressed on the receiver input, as required.

While we have described a preferred form and several modifications of our invention, it is to be understood that the invention is in no way limited to the precise arrangements shown. For

example, multigrid keying tubes may be used in order to separate more readily the rectifying circuit from the radio frequency circuit, and yet to maintain the dual functions of the keying tubes.

We claim as our invention:

1. In a device of the character described, a

source of alternating current, means for rectifying said alternating current to produce a direct current, a receiver, means for applying said direct current to energize said receiver, a source of radio frequency currents, and means including a current path for said radio frequency currents through said rectifying means for applying said radio frequency currents to the input of said receiver.

2. In a device of the character described, a radio receiver having an input circuit, an antenna, keying means for applying signal currents from said antenna to said input circuit, said keying means including means for periodically reversing the phase of said currents, and means including said keying means for supplying a direct current for energizing said receiver.

3. In a device of the character described, a radio receiver having an input circuit, an antenna, keying means connecting said antenna to said input circuit, and a source of alternating current, said keying means being energized by said alternating current to periodically reverse the phase of signal currents derived from said antenna, and said keying means also rectifying said alternating current to produce a direct current for the operation of said receiver.

4. In a device of the character described, a radio receiver having an input circuit for radio frequency currents and an input circuit for direct currents, a source of radio frequency currents, a pair of discharge devices for connecting said source of radio frequency currents tosaid radio frequency input circuit, a source of alternating current, means for applying said alternating current to said devices to cause said devices to apply radio frequency currents of successively opposite polarity to said radio frequency input circuit, means for deriving a rectified direct current from said devices, and means for applying said derived currents to said direct current input circuit.

5. In a device of the character described, a radio device having input circuits for radio frequency currents and direct currents respectively, a source of radio frequency currents, keying means connecting said source of radio frequency currents to said radio frequency input circuit and for applying radio frequency currents of successively opposite phase to said radio frequency input circuit, a source of alternating ourrent, means including said keying means for rectifying said alternating current to produce a direct current, and means for applying said direct current to said direct current input circuit.

6. In a device of the character described, a radio device having input circuits for radio frequency currents and direct currents, respectively, a source of radio frequency currents, a pair of discharge devices, means for applying to said discharge devices radio frequency currents of respectively opposite phase from said source, a source of low frequency alternating currents, means for applying said low frequency currents to said discharge devices to cause said devices to become alternately conductive, means for impressing on said radio frequency input circuit 7 radio frequency currents derived from said discharge devices, means for deriving a rectified current from said discharge devices, and means for impressing said rectified current on said direct current input circuit.

7. In a device of the character described, a radio device having radio frequency and direct current input circuits, a source of alternating current, a source of radio frequency currents, comnion means for rectifying said alternating current and for applying said radio frequency currents to said radio frequency input circuit, and means for impressing said rectified current on said direct current input circuit.

8. In a device of the character described, a radio device having input circuits for radio frequency currents and direct currents, respectively, a loop antenna, a pair of discharge devices having cathode and anode electrodes, means for coupling respective terminals of said loop antenna to said anode electrodes, means for causing ductive, means in circuit with said cathode elec- I trodes for deriving a radio frequency current and a direct current, and means for applying said derived currents to the corresponding input circuits of said device.

9. In a device of the character described, a radio device having input circuits for radio frequency currents and direct currents, respectively, a loop antenna, a pair of discharge devices having cathode and anode electrodes, means for coupling respective terminals of said loop antenna to said anode electrodes, means for applying a low frequency alternating current to said anode electrodes so as to cause said discharge devices to become alternately conductive, means in circuit with said cathode electrodes for deriving a radio frequency current and a direct current, and means for applying said derived currents to the corresponding input circuits of said device.

10. In a device of the character described, a radio device having input circuits for radio frequency currents and direct currents, respectively, a directional antenna, a pair of discharge devices having grid, cathode and anode electrodes, means for applying out of phase currents from said antenna to said grid electrodes, means for applying a low frequency alternating current to said anode electrodes so as to cause said discharge devices to become alternately conductive, means for coupling said anode electrodes to said radio frequency input circuit, means in circuit with said cathode electrodes for deriving a rectified current, and means for applying said rectified current to said direct current input circuit.

PHILIP G. COOPER. CLARENCE D. TUSKA. 

